The invention concerns a machine arrangement with a first machine having a first rotation connection, a second machine having a second rotation connection, and a shaft for transmission of a torque, the shaft being unrotatably connected with both rotation connections.
The term "machine" covers any device, which produces a torque, for example motors, absorbs a torque, for example pumps, generators or driven machines, convert a torque, for example gears and driving elements, or simply pass on a torque, for example shafts.
For reasons of clarity, the following description of the invention is based on a machine arrangement comprising a hydraulic motor and a gear, the shaft transmitting the torque from the hydraulic motor to the gear.
In a machine arrangement of this kind, the gear housing is fixedly connected with the motor housing. Usually, the fixing is made by means of flanges. In this connection it must be ensured that the outlet shaft of the motor and the inlet shaft of the gear are in alignment, that is have a common rotation axis. When this alignment is not provided, the life of one of the two machines will be substantially reduced, for example due to a wrong bearing load. Deviations in the positioning may for example appear in that the machines are mounted laterally offset in relation to each other, so that the rotation axes of the outlet shaft of the motor and the inlet shaft of the gear are laterally offset, but parallel to each other. Another positioning error could be that the two rotation axes form an angle with each other. Of course, both error possibilities can also be combined.
Problems caused by wrong alignments can also be avoided in that the shaft is made as a cardan shaft. However, this process is both complicated and expensive.